The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, the approaches described in this section may not be prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
For a wireless communication system to achieve its maximum throughput and link quality the impact of outside radio frequency (RF) interference on the communication link must be minimized. Interference occurs when devices other than those used in the communication system emit energy in the same RF spectrum that the communication system uses.
Link performance of a wireless communication system can also be degraded by interference from devices that use the same protocol as the communication system but do not communicate with the communication system. When multiple devices operate in the same communications channel they must share the bandwidth of the communications channel and therefore only obtain a fraction of the throughput they could achieve if they were operating alone in the communications channel.
Interference is common when a wireless communication system operates in an unlicensed band where several other wireless devices are allowed to communicate in the same spectrum. For example, an 802.11b/g communication system operates in the 2.4-2.5 GHz Industrial, Scientific, and Medical (ISM) radio band. Other consumer devices such as microwave ovens, cordless phones, and Bluetooth devices are also permitted to operate in this band. If one of these devices emits a signal using the same frequency spectrum and at the same time as the 802.11b/g communication system, then the throughput and link quality achieved by the communication system can be significantly reduced.
In a multi-channel communication system where the communication system has the ability to operate on different channels, the best way to mitigate the interference problem is to detect the interference and avoid it by switching to another communications channel that has less interference or ideally, no interference. This is typically accomplished by performing measurements on a set of available communications channels and selecting a particular communications channel that is determined to have the least amount of current activity. One problem with this approach is that it does not account for dynamic noise environments or situations where a mobile device moves into a different noise environment. Another approach is to employ frequency hopping on a set of “good” channels, i.e., communications channels that are known to have little or no interference as of the last time that measurements were taken. Using frequency hopping over multiple channels can be a better solution than using a single communication channel because it reduces the likelihood of interference completely blocking communications. Frequency hopping systems, however, may be more difficult to implement, less efficient in bandwidth utilization and are still adversely affected by dynamic noise environments and situations where a mobile device moves into a different noise environment.
In view of the foregoing, an approach for selecting communications channels in communication systems to avoid interference that does not suffer from the limitations of prior approaches is highly desirable.